If you or someone you love has been experiencing memory problems, confusion, or changes in thinking, you may be wondering: How do doctors test for Alzheimer’s disease?
The good news is that there are more ways than ever to evaluate memory loss and identify the underlying cause. From simple memory screenings to advanced brain scans and blood tests, healthcare professionals have several tools available to help determine whether someone may have Alzheimer’s disease or another form of dementia.
However, there isn’t just one test that can diagnose Alzheimer’s. Doctors typically use a combination of assessments, medical history, laboratory tests, and specialized diagnostic procedures to reach an accurate diagnosis.
Understanding the different types of Alzheimer’s tests can help you know what to expect, when to seek an evaluation, and why early detection matters.
1. Cognitive Screening Tests (Memory Tests)
One of the first steps in evaluating possible Alzheimer’s disease is a cognitive screening test. These tests are designed to evaluate memory, attention, language, problem-solving, and other thinking abilities.
They are typically brief, noninvasive assessments that can be administered in a doctor’s office or by a qualified healthcare professional.
Some commonly used cognitive screening tests include:
- Mini-Mental State Examination (MMSE): A series of questions and tasks that evaluate orientation, memory, attention, language, and basic cognitive skills.
- Montreal Cognitive Assessment (MoCA): A screening tool that evaluates several areas of thinking, including short-term memory, executive function, attention, and language. It can help identify mild cognitive impairment.
- Mini-Cog: A brief assessment that combines a three-word recall exercise with a clock-drawing task.
- Saint Louis University Mental Status Examination (SLUMS): A screening assessment that evaluates memory, attention, orientation, and other cognitive abilities.
What do these tests tell doctors?
Cognitive screening tests help identify possible problems with thinking and memory. They can indicate whether someone may need additional evaluation, but they cannot independently diagnose Alzheimer’s disease.
A person can also perform well on a brief screening test and still experience meaningful changes in everyday life. That’s why doctors consider the person’s symptoms, medical history, and concerns from family members alongside test results.
2. Neuropsychological Testing
Sometimes a brief memory screening isn’t enough to understand what’s happening. In these situations, a doctor may recommend a more comprehensive neuropsychological evaluation.
Unlike a short screening, neuropsychological testing involves a series of detailed assessments that may take several hours.
These tests evaluate multiple areas of brain function, including:
- Short-term and long-term memory
- Attention and concentration
- Language and communication
- Problem-solving and reasoning
- Planning and organization
- Visual and spatial abilities
- Processing speed
What do these tests tell doctors?
Neuropsychological testing can help identify specific patterns of cognitive difficulty. These patterns may provide clues about whether someone is experiencing Alzheimer’s disease, another type of dementia, or a different condition affecting cognitive function.
It can also help distinguish normal age-related forgetfulness from mild cognitive impairment or more significant cognitive decline.
3. Blood Tests
Blood tests are an important part of evaluating memory loss. Some are used to identify medical conditions that can cause symptoms similar to dementia, while newer tests can detect biological markers associated with Alzheimer’s disease.
Blood tests that look for other causes of memory loss
Not all memory problems are caused by Alzheimer’s. Certain medical conditions can affect thinking and memory, and some are treatable.
A doctor may order blood tests to check for:
- Vitamin B12 deficiency: Low B12 levels can contribute to memory problems, confusion, and other neurological symptoms.
- Thyroid disorders: An underactive or overactive thyroid can affect concentration, memory, and mental function.
- Blood sugar abnormalities: Diabetes and significant blood sugar fluctuations can affect cognitive function.
- Electrolyte imbalances: Abnormal levels of certain minerals in the blood can contribute to confusion and cognitive changes.
- Anemia and other medical conditions: Certain blood disorders and underlying illnesses may contribute to fatigue, confusion, and difficulty concentrating.
Finding and treating an underlying medical problem may improve cognitive symptoms.
Blood tests that look for Alzheimer’s biomarkers
One of the biggest developments in Alzheimer’s diagnosis is the emergence of blood tests that look for specific proteins associated with the disease.
Researchers have identified biological markers, including amyloid-beta and phosphorylated tau (p-tau), that are associated with the changes occurring in the brains of people with Alzheimer’s.
In May 2025, the FDA cleared the first blood test specifically intended to aid in diagnosing Alzheimer’s disease: the Lumipulse G pTau217/β-Amyloid 1-42 Plasma Ratio.
The test measures two proteins in the blood and helps identify the presence of amyloid plaques associated with Alzheimer’s disease. It is intended for adults age 55 and older who are already experiencing symptoms and undergoing a clinical evaluation.
Additional blood-based biomarker tests have also entered clinical practice.
Are blood tests enough to diagnose Alzheimer’s?
Not necessarily. Blood-based Alzheimer’s tests are an important advancement, but they must be interpreted alongside a person’s symptoms, cognitive assessments, and other clinical information.
These tests are not intended to be general screening tests for people who have no symptoms. Their appropriate use depends on the specific test and the patient’s circumstances.
4. Brain Imaging Tests
Doctors may use brain imaging to look for physical changes in the brain, identify potential causes of memory loss, and help distinguish Alzheimer’s from other conditions.
There are several different types of brain scans.
MRI (Magnetic Resonance Imaging)
An MRI uses magnetic fields and radio waves to create detailed images of the brain.
An MRI can help doctors identify:
- Brain shrinkage (atrophy) in certain regions
- Evidence of previous strokes
- Blood vessel damage
- Brain tumors or other structural abnormalities
- Other conditions that may contribute to memory problems
Certain patterns of brain shrinkage may be consistent with Alzheimer’s disease, but an MRI alone cannot confirm the diagnosis.
CT Scan (Computed Tomography)
A CT scan uses X-rays to create images of the brain.
It can help identify structural problems such as:
- Brain tumors
- Bleeding
- Previous strokes
- Fluid buildup
- Other abnormalities that may affect cognitive function
CT scans are sometimes used when an MRI isn’t appropriate or readily available.
Like an MRI, a CT scan cannot independently diagnose Alzheimer’s disease.
PET Scan (Positron Emission Tomography)
A PET scan is a specialized imaging test that allows doctors to examine activity or specific biological substances in the brain.
There are different types of PET scans used in dementia evaluations.
Amyloid PET scans: These scans look for amyloid plaques, one of the hallmark biological features of Alzheimer’s disease.
Tau PET scans: These scans look for abnormal tau protein accumulation, another characteristic of Alzheimer’s.
FDG-PET scans: These measure glucose metabolism in the brain. Certain patterns of reduced brain activity can help doctors distinguish Alzheimer’s from other forms of dementia.
PET scans can provide valuable diagnostic information, particularly when the cause of cognitive symptoms is unclear. However, not everyone needs one.
5. Cerebrospinal Fluid (CSF) Testing
Another way doctors can look for biological evidence of Alzheimer’s is by testing cerebrospinal fluid (CSF).
CSF is the clear fluid that surrounds and protects the brain and spinal cord.
To collect a sample, a healthcare professional performs a procedure called a lumbar puncture, commonly known as a spinal tap. A small needle is inserted into the lower back to collect fluid for laboratory testing.
The sample can be analyzed for levels of proteins associated with Alzheimer’s disease, including:
- Amyloid-beta 42
- Total tau
- Phosphorylated tau
Abnormal levels or ratios of these proteins can provide evidence of Alzheimer’s-related changes in the brain.
Is a spinal tap necessary to diagnose Alzheimer’s?
No. CSF testing is not necessary for everyone. Doctors may recommend it when they need additional information to clarify a diagnosis or determine whether someone has the biological changes associated with Alzheimer’s disease.
6. Neurological and Physical Examinations
A doctor may also perform a physical and neurological examination as part of the diagnostic process.
These examinations help identify physical signs that could point to other conditions affecting the brain and nervous system.
A neurological exam may evaluate:
- Reflexes
- Muscle strength
- Coordination and balance
- Walking and movement
- Eye movements
- Speech
- Sensation
Doctors may also evaluate blood pressure, heart health, and other aspects of overall physical health.
These examinations help rule out other possible explanations for symptoms and provide a more complete picture of a person’s health.
7. Depression and Mental Health Screenings
Did you know that depression, anxiety, and other mental health conditions can sometimes cause symptoms that look like dementia?
Depression, in particular, can affect memory, concentration, motivation, and the ability to complete everyday tasks.
Because these symptoms can overlap with those of Alzheimer’s disease, doctors may conduct a depression screening or psychological evaluation.
They may ask questions about:
- Mood changes
- Loss of interest in activities
- Sleep disturbances
- Anxiety
- Changes in appetite
- Difficulty concentrating
- Feelings of hopelessness
Identifying depression or another mental health condition is important because appropriate treatment may improve cognitive symptoms.
However, depression and Alzheimer’s can also occur at the same time, so one does not automatically rule out the other.
8. Genetic Testing for Alzheimer’s Disease
You may have heard that Alzheimer’s can run in families. While genetics can influence a person’s risk, most cases of Alzheimer’s are not caused by a single inherited genetic mutation.
There are two main types of genetic testing that may come up during an Alzheimer’s evaluation.
APOE genetic testing
The APOE gene has several variations. Having one or two copies of the APOE-e4 variant increases the risk of developing Alzheimer’s, but it does not mean someone will definitely develop the disease.
APOE testing is not a stand-alone diagnostic test.
It may also be discussed when evaluating certain Alzheimer’s treatment options, because APOE-e4 status can affect the risk of serious treatment-related side effects.
Familial Alzheimer’s genetic testing
In rare families, Alzheimer’s is caused by inherited mutations in genes such as APP, PSEN1, and PSEN2.
These mutations are associated with autosomal dominant Alzheimer’s disease, which often begins at a younger age.
Genetic testing may be considered when there is a strong family history of Alzheimer’s across multiple generations, particularly when symptoms begin relatively early.
Because genetic testing can have significant implications for family members, genetic counseling is recommended before and after testing.
Which Alzheimer’s Test Is the Most Accurate?
There isn’t one test that is best for every person.
Different tests provide different types of information. A cognitive screening can identify possible memory problems, while blood tests, spinal fluid testing, and specialized PET scans can help identify biological changes associated with Alzheimer’s.
In many cases, doctors combine several approaches to reach a diagnosis.
The appropriate testing depends on factors such as:
- The person’s age
- Their symptoms and how long they’ve been experiencing them
- Their medical history
- Their family history
- Results of initial cognitive assessments
- Whether other conditions could explain the symptoms
The goal is not simply to determine whether someone has memory problems. It’s to understand why those problems are occurring.
Why Is Early Alzheimer’s Testing Important?
Many people delay seeking an evaluation because they assume memory changes are simply a normal part of aging. Others may be afraid of what a diagnosis could mean.
But identifying Alzheimer’s disease or another form of dementia early can make a meaningful difference.
An early diagnosis can help individuals and families:
- Explore available treatment options.
- Address medical conditions that may be contributing to memory problems.
- Make important financial, legal, and future care decisions.
- Understand what changes to expect as the disease progresses.
- Connect with caregiver education and support services.
- Plan for the future while the person with memory changes can still actively participate.
There are also treatments available for certain people in the early stages of Alzheimer’s that may help slow the progression of symptoms. Early evaluation can help determine whether someone may be eligible.
Most importantly, an Alzheimer’s diagnosis does not mean life is over. With the right information, support, and planning, individuals and families can continue to find meaningful ways to live well.
Where Can You Get a Memory Screening in Smith County?
If you’ve noticed changes in your memory or are concerned about a loved one’s cognitive health, taking the first step can feel overwhelming.
The Alzheimer’s Alliance of Smith County offers free memory screenings to help individuals identify potential concerns and determine whether further evaluation may be appropriate.
Memory screenings are not diagnostic tests and cannot determine whether someone has Alzheimer’s disease. However, they can be a helpful starting point for recognizing possible changes and encouraging individuals to speak with their healthcare provider.
The Alliance offers free memory screenings through its Wellness Wednesday program on the first Wednesday of each month.
If you or someone you love has concerns about memory loss, don’t wait until the symptoms become more noticeable. Early conversations and evaluations can help you better understand what’s happening and what steps to take next.
Contact the Alzheimer’s Alliance of Smith County:
Phone: 903-509-8323
Email: info@alzalliance.org
Website: www.alzalliance.org
3531 S. Broadway Ave., Tyler, TX
You don’t have to navigate memory loss or a dementia diagnosis alone. The Alzheimer’s Alliance of Smith County is here to provide education, resources, and support for individuals and families throughout our community.
Frequently Asked Questions About Alzheimer’s Testing
Is there a single test that can diagnose Alzheimer’s disease?
No. Alzheimer’s is diagnosed through a combination of medical history, cognitive assessments, physical and neurological examinations, and, when appropriate, laboratory tests, brain imaging, and specialized biomarker testing.
Can a regular blood test detect Alzheimer’s?
Some newer blood tests can detect proteins associated with Alzheimer’s disease. However, they are used as part of a clinical evaluation for people experiencing cognitive symptoms, not as general screening tests for everyone.
At what age should someone get tested for Alzheimer’s?
There is no single age at which everyone should be tested. Anyone experiencing persistent or concerning changes in memory, thinking, or behavior should discuss those symptoms with a healthcare provider, regardless of age.
Can an Alzheimer’s test be wrong?
Yes. No diagnostic test is perfect. Some tests can produce false-positive or false-negative results, and results must be interpreted in the context of the person’s symptoms and overall health.
Does a normal memory screening mean someone doesn’t have Alzheimer’s?
No. A normal screening result does not completely rule out Alzheimer’s or another cognitive condition. If memory problems continue or worsen, a more comprehensive evaluation may be appropriate.
Can memory problems be reversed?
Some causes of memory problems, such as certain vitamin deficiencies, medication side effects, thyroid disorders, and depression, may improve with appropriate treatment. Alzheimer’s disease itself is progressive, but identifying the cause of memory changes is an important first step.
What is the difference between a memory screening and an Alzheimer’s diagnostic test?
A memory screening is a brief assessment designed to identify possible cognitive concerns. A diagnostic evaluation is more comprehensive and is performed by a healthcare provider to determine the underlying cause of those concerns.
